JP6509202B2 - Process for producing FCC catalyst with reduced attrition rate - Google Patents

Description

  The present invention is a novel fluid catalytic cracking catalyst (FCC catalyst) containing microspheres comprising faujasite-type zeolite of type Y and having very high activity and other desirable properties, the preparation of said catalyst The invention relates to a process and to the use of the catalyst for cracking petroleum feedstocks, in particular in processes with short residence times.

  Since the 1960's, most commercial fluid catalytic cracking catalysts contain zeolite as the active ingredient. Such catalysts are in the form of small particles, called microspheres, which contain both active and non-zeolitic components. Non-zeolitic components are often referred to as a matrix for the zeolitic component of the catalyst. Non-zeolitic components are known to perform several important functions related to both the catalytic and physical properties of the catalyst. Oblad describes these features as follows: "This matrix acts as a hole for sodium in the sieve, and is thus said to provide stability to the zeolite particles in the matrix catalyst. This matrix provides additional functions as follows: The matrix dilutes the zeolite; stabilizes the zeolite against heat and steam and mechanical attrition; provides high porosity so that the zeolite can be used at its full capacity and can be regenerated easily; And finally, it provides bulk properties that are important for heat transfer when performing regeneration and cracking and heat storage in large scale catalytic cracking. A. G. Oblad Molecular Sieve Cracking Catalysts, The Oil And Gas Journal, 70, 84 (Mar. 27, 1972).

  In conventional fluid catalytic cracking catalysts, the active zeolite component is incorporated into the microspheres of the catalyst by one of two general techniques. In one technique, the zeolite component is crystallized and then incorporated into microspheres in a separate step. In the second technique, the in situ technique, the microspheres are first formed and then the zeolite component is crystallized in the microspheres themselves, resulting in microspheres comprising both the zeolitic component and the non-zeolitic component .

  It has long been recognized that fluid catalytic cracking catalysts must have commercially acceptable activity, selectivity, and stability for commercial success. Such catalysts must have sufficient activity to yield economically attractive yields, produce sufficient selectivity to produce the desired product and not produce the undesired product. It must have sufficient thermal stability and attrition resistance to have a commercially useful life.

  In general, the FCC is commercially practiced cyclically. During this operation, the hydrocarbon feed is contacted with the hot, active solid particulate catalyst at a pressure of, for example, about 50 psig or less and at a temperature of about 650 ° C. or less without hydrogenation. The catalyst is a powder having a particle size of about 20 to 200 micrometers in diameter and an average size of about 60 to 100 micrometers. The powder is propelled upward through the riser reaction zone to be fluidized and thoroughly mixed with the hydrocarbon feed. The hydrocarbon feedstock is catalytically cracked at the aforementioned high temperatures and separated into various hydrocarbon products. As the hydrocarbon feedstock is cracked in the presence of a cracking catalyst to form gasoline and olefins, undesirable carbonaceous residues known as "coke" deposit on the catalyst. The spent catalyst also contains the metals present in the feed in addition to the coke. Catalysts for FCC are typically large pore aluminosilicate compositions, including faujasite or zeolite Y.

  The coke-adhered catalyst particles are separated from the cracked hydrocarbon product and stripped and transferred to a regenerator where the coke is burned off to regenerate the catalyst. The regenerated catalyst then flows downwardly from the regenerator to the riser bottom.

  Such cracking and regeneration cycles at high flow rates and high temperatures tend to physically break the catalyst into smaller particles called "fines". Such fines have a diameter of 20 micrometers or less, while the average diameter of the catalyst particles is about 60 to about 100 micrometers. An important parameter in determining the unit residence of the catalyst and thus its cost efficiency is attrition resistance. The initial size of the particles can be adjusted by controlling the initial spray drying of the catalyst, but with poor attrition resistance, the catalytic cracking unit should not be released into the atmosphere 0 to 20 micrometers. May produce a large amount of fines. Commercial catalytic crackers include cyclones and electrostatic precipitators that prevent fines from floating in air. One skilled in the art also recognizes that excessive catalyst fines formation increases refinery catalyst costs. Excess fines can lead to increased catalyst loading and catalytically effective particle dilution.

  U.S. Pat. No. 4,493,902 shows new attrition resistant high zeolite content catalytically active microspheres comprising more than about 40% by weight, preferably 50 to 70% by weight, of Y-faujasite Flow decomposition catalysts and chemically reactive calcined clays, ie metakaolins (kaolins that are calcined and thereby undergo a strong endothermic reaction with dehydroxylation), and used to convert kaolin to metakaolin A porous material composed of a mixture of two forms: kaolin clay calcined under conditions more severe than the above conditions, ie, kaolin clay characteristic reaction caused by calcination sometimes called spinel form of calcined kaolin Disclosed is a process for the preparation of said catalyst by crystallizing> 40% sodium Y-zeolite in microspheres. Cage, which is incorporated the teachings of the patent specification as to constitute a part of this specification here. In a preferred embodiment, microspheres comprising two forms of these calcined kaolin clays are immersed in an alkaline sodium silicate solution, which preferably has the maximum amount of Y-faujasite obtainable. It is heated until it crystallizes in the microspheres.

In the practice of the technology described in US Pat. No. 4,493,902, porous microspheres in which the zeolite is crystallized are preferably produced as follows. That is, finely pulverized raw material (hydrated) kaolin clay (Al ₂ O ₃ : ₂ SiO ₂ : 2 H ₂ O), finely pulverized kaolin clay calcined through heat generation, and a minor amount of sodium silicate Manufactured by forming an aqueous slurry of Here, the sodium silicate acts as a fluidizing agent for the slurry charged to the spray dryer to form the microspheres and then physically coalesce into the components of the spray dried microspheres Perform the function of giving sex.

  Spray-dried microspheres comprising a mixture of hydrated kaolin clay and kaolin that has undergone an exotherm by firing are then fired under controlled conditions that are more moderate than those required to exotherm the kaolin, whereby the microspheres The hydrated kaolin clay portion of is dehydrated and this portion is converted to metakaolin, which results in microspheres comprising the desired mixture of metakaolin and caloric kaolin and sodium silicate binder upon calcination. In the example of U.S. Pat. No. 4,493,902, approximately equal masses of hydrated clay and spinel are present in the spray dryer feedstock, and the resulting fired microspheres are more exothermic than metakaolin. Contain somewhat more clay. U.S. Pat. No. 4,493,902 shows that calcined microspheres contain about 30 to 60% by weight of metakaolin and about 40 to 70% by weight of kaolin characterized by its characteristic exotherm I teach. A less preferred method described in U.S. Pat. No. 4,493,902 involves spray drying of a slurry comprising a mixture of kaolin clay pre-calcined in the metakaolin state and kaolin which has been exothermed by calcination. However, in this slurry, the hydrated kaolin is not contained at all, so that the microspheres containing both metakaolin and kaolin which has generated heat due to calcination are converted into hydrated kaolin into metakaolin by calcination. It is brought directly.

  In the practice of the invention described in U.S. Pat. No. 4,493,902, microspheres composed of kaolin and metakaolin which generate heat by firing are in the presence of a crystallization initiator (seed crystal). It reacts with sodium hydroxide solution which is rich in sodium hydroxide, thereby converting silica and alumina in microspheres into synthetic sodium faujasite (Y-type zeolite). The microspheres are separated from the sodium silicate mother liquor and ion exchanged with rare earth, ammonium ions or both to form various known stabilized forms of rare earth or catalyst. The technology described in U.S. Pat. No. 4,493,902 is a means for achieving the desired unique combination of high zeolite content with high activity, good selectivity and thermal stability and attrition resistance. I will provide a.

  The technology has had widespread commercial success. Due to the availability of high zeolite content microspheres that also have this attrition resistance, refineries that target specific performance, such as improved activity and / or selectivity, now suffer from costly mechanical redesigns. Custom-designed catalysts can be used without it. Most of the FCC catalysts currently supplied to domestic and foreign refineries are based on this technology. Refineries where FCC units are constrained by the highest acceptable regenerator temperature or blast capacity are pursuing increased selectivity, thereby reducing coke formation while limiting gas compressors to gas Catalysts that reduce generation are highly desirable. The seemingly slight reduction in coke can mean significant economic benefit to the operation of an FCC unit subject to blower or regenerator temperature constraints.

  The activity and selectivity of the catalyst formed by the method described in U.S. Pat. No. 4,493,902 is generally lower than the fluid catalytic cracking catalyst produced by incorporating the zeolite into the matrix. Even with full porosity is achieved. In particular, such catalyst microspheres may have a total porosity of less than about 0.15 cc / g or even less than about 0.10 cc / g. Overall, the microspheres described in US Pat. No. 4,493,902 have a total porosity of less than 0.30 cc / g. As used herein, "total porosity" means the volume of pores having a diameter in the range of 35-20,000 Å as measured by mercury porosimetry techniques. In U.S. Pat. No. 4,493,902, it is surprising that microspheres having a total porosity of less than about 0.15 cc / g exhibit activity and selectivity as found therein. It is stated that there is. Such results are, for example, in contrast to the prior art disclosure that low pore volumes can lead to reduced selectivity because diffusion is limited.

  The relatively low porosity of the microsphere catalyst formed as described in US Pat. No. 4,493,902 is not believed to adversely affect activity and selectivity. This is because the microspheres described in U.S. Pat. No. 4,493,902 are not diffusion limited in the case of typical FCC process conditions used at the time of that patent. In particular, the contact time between the feedstock to be cracked and the catalyst is typically 5 seconds or more. Thus, although the typical FCC catalyst formed by mechanically incorporating the zeolite inside the matrix may have a higher porosity, the reaction time in the prior art FCC riser is There was no benefit to either nor the selectivity. This result led to the conclusion that, for the FCC catalyst, at least outside the zeolite structure, the transport process was not a limiting factor at all. Objections to this contradict the facts and are easily dismissed as selfish. Importantly, the attrition resistance of the microspheres prepared according to U.S. Pat. No. 4,493,902 is to a conventional FCC catalyst where the crystallized zeolite catalyst component is physically incorporated into the non-zeolite matrix. It was better than it was.

  More recently, however, FCC units have been developed which dramatically reduce the contact time between the catalyst and the feedstock to be cracked. Usually, the reactor is a riser, in which catalyst and hydrocarbon feed enter at the bottom and are transported in. As the hydrocarbon passes through the riser and exits the riser, the hot catalyst cracks it and cracking products are separated from the catalyst. The catalyst is then sent to the regenerator where coke is removed, thereby purifying the catalyst while providing the necessary heat to the catalyst in the riser reactor. Modern riser reactors are operated with shorter residence times and higher operating temperatures to minimize coke selectivity and delta coke. Not all risers are used, and some designs have contact times reduced to less than a second. As a result of the improvement of the device, the selectivity of gasoline and drying gas can be improved. The FCC unit thus improved is marketed as useful regardless of the type of catalyst purchased, which implies that there is no systematic problem with conventional catalyst technology. It shows.

  The fact that heavier feedstocks are processed in FCC type processes, and the tendency of such feedstocks to increase coke formation and lead to undesirable products also results in contacting the feedstock with the catalyst. It is the reason that a new method was introduced. Of particular interest has been the method of contacting the FCC catalyst for a very short contact period. For example, it has been found that short contact times of less than 3 seconds and extremely short contact times of less than 1 second in the riser improve the selectivity to gasoline while reducing the formation of coke and drying gas.

  In the FCC process, the activity of the "equilibrium" catalyst used tends to be higher to compensate for the progressively shorter contact time of the catalyst with the oil. For example, the total surface area of the catalyst needs to be increased, and the amount of rare earth oxide promoter added to the catalyst is also increasing. In addition, the cracking temperature is also rising to compensate for the reduction in conversion. Unfortunately, it has been found that after conversion of the unit, the API gravity of the bottom product, which occurs during short contact times (SCT), often increases, which results in the cracking of the very heavy parts of the hydrocarbon feed It is also said that it takes a relatively long time. Furthermore, although it is appreciated that the total surface area of the catalyst is large, the FCC method is still highly rated for attrition resistance. Thus, it is increasingly considered that optimization of the FCC catalyst will be necessary for the process currently using new short contact times and very short contact times, which are not obvious to the person skilled in the art. It has become.

  It is currently believed that in methods of treating hydrocarbons with short contact times, further improvement is obtained by eliminating the diffusion limitations still present in current catalysts. This is becoming to be concluded that even such materials are superior in application. It is believed that such improvements in the catalyst can be obtained by optimizing the porosity of the catalyst and eliminating the active site plugging and diffusion limitations of the binder phase present in the so-called incorporated catalyst.

  In U.S. Patent No. 6,943,132 assigned to the assignee of the present invention, the alumina rich non-zeolite matrix of the catalyst is such that 90% by weight of the hydrous kaolin particles are less than 2 micrometers. It has been found that macroporous zeolite microspheres can be produced when derived from ultrafine hydrous kaolin sources having a diameter, pulverized and exothermally calcined.

  The ultrafine hydrous kaolin is dried in a spray dryer or suitable unit operation and then deagglomerated using a high energy grinder or dry grinding means. By carrying out this unit operation, agglomerates are reduced, and by returning them to the calciner feed, a particle size similar to that measured in the slurry as described above is obtained. The presence of the aggregate structure changes the particle size and bulk density characteristics of the calcined kaolin. Flocculation and sintering occur during phase change from hydrous kaolin. The particle size measured is coarse over the entire particle size range. Large agglomerated structures have higher density and thus lower porosity. The pore volume is increased by the bonding of the particle contact points by structuring before calcination, which in the case of fully calcined kaolin is maintained by the theoretically released amorphous silica. The thermal transition to spinel releases one mole of silica per mole of spinel formed. An additional 4 moles are released by the mullite transition from spinel.

  More generally, the FCC catalyst matrix useful in the invention to achieve the macroporosity of the FCC catalyst has a specific water pore volume different from the prior art calcined kaolin used to form the catalyst matrix. And derived from an alumina source, such as kaolin, which has been calcined via an exotherm. The water hole volume was derived by the Incipient Slurry Point (ISP) test and is described in the patent.

The morphology of the microsphere catalyst formed as described in US Pat. No. 6,943,132 is unique to previous in situ formed microsphere catalysts. The use of finely divided ultrafine hydrous kaolin, which has been calcined via heat generation, results in in situ zeolite microspheres having a porous structure in which the macropores of the structure are substantially coated or lined with zeolite after crystallization. Will be brought. Macroporosity, as defined herein, means that the catalyst has a macropore volume in the pore range of 600-20,000 Å with a mercury intrusion of at least 0.07 cc / gm. Also, this catalyst has a BET surface area of less than 500 m ² / g. This novel catalyst is optimal for FCC processes involving short contact time processes in which the hydrocarbon feedstock contacts the catalyst for a time less than about 3 seconds.

  The high porosity within the microspheres is important to maximize catalytic activity by eliminating the typical ratio drop resulting from the diffusion of crude oil molecules within the microsphere structure. However, as the porosity of the microspheres increases, the ratio of microsphere breakage and attrition to finer particles within the FCC unit operating environment increases, thereby increasing the addition of fresh catalyst, and from the unit. Particle emissions increase. Process or compositional mechanisms for reducing the attrition rate of FCC catalysts at a given total pore volume are of fundamental importance in order to improve the performance and corresponding utility of the catalyst.

SUMMARY OF THE INVENTION Improved attrition resistance is formed in situ (by in situ formation) by adding a cationic polyelectrolyte to a kaolin slurry and then processing it into a microsphere substrate for subsequent zeolite growth ) To the FCC catalyst.

Figure 2 is a plot of air jet attrition results for the catalyst according to the invention and the comparative catalyst against the pore volume of the catalyst. Figure 2 is a plot of roller attrition results against pore volume of the catalyst. Figure 2 is a plot of air jet attrition results for the catalyst according to the invention and the comparative catalyst against the pore volume of the catalyst. Figure 2 is a plot of roller attrition results against pore volume of the catalyst.

Detailed Description of the Invention The microsphere catalyst of the present invention is prepared by the generic method disclosed in US Patent 4,493,902 assigned to the assignee of the present invention. The alumina-rich non-zeolite matrix of the catalyst of the present invention is derived from a hydrous kaolin source which is in the form of an ultrafine powder, as disclosed herein in the aforementioned US Pat. No. 6,943,132. Preferably at least 90% by weight of the ultrafine powder is less than 2.0 micrometers, preferably at least 70% by weight less than 1 micrometer. The ultra-fine water-containing kaolin is finely pulverized and is subjected to heat generation and firing. It is also within the scope of the present invention that the zeolite microspheres are formed using an alumina-rich matrix derived from kaolin having a larger size, and calcined at least substantially through its characteristic exotherm . Satintone® No. 1 (commercially available kaolin calcined via its characteristic exotherm without substantial formation of mullite) is used on a commercial basis to form an alumina rich matrix It is a material. Satintone® No. 1 is derived from hydrous kaolin where 70% of the particles are less than 2 micrometers. Other sources used to form the alumina-rich matrix include finely divided hydrated kaolin [e.g. ASP.RTM. 600, i.e. "Aluminum Silicate Pigments", calcined at least substantially via its characteristic exotherm]. (EC-1167), a commercially available hydrous kaolin described in Engelhard's technical notification No. TI-1004. Booklet clay is the most widely used commercially and has a great deal of global success.

  The general method of producing the FCC microspheres of the present invention is well known in the prior art and can be according to the method disclosed in US Pat. No. 4,493,902. As disclosed in U.S. Pat. No. 4,493,902, reactive finely particulate hydrous kaolin and / or metakaolin and an alumina-containing material forming a matrix, such as calcined through its characteristic heat generation An aqueous slurry with ultrafine kaolin is prepared. The aqueous slurry is then spray-dried to form a mixture comprising hydrous kaolin and / or metakaolin and a mixture of kaolin calcined at least substantially via its characteristic exotherm to form a high alumina matrix. A sphere is obtained. Preferably, an appropriate amount of sodium silicate is added to the aqueous slurry before the aqueous slurry is spray dried to act as a binder between kaolin particles.

  The reactive kaolin of the slurry to form the microspheres may be formed from hydrated kaolin or calcined hydrous kaolin (metakaolin) or mixtures thereof. The hydrous kaolin of the feedstock slurry may suitably be any one or a mixture of ASP® 600 or ASP® 400 kaolin derived from a coarse white kaolin feedstock. It is also possible to use hydrous kaolins of smaller particle size, which include kaolins obtained from gray clay layers, such as, for example, LHTR pigments. Purified water treated kaolin clay obtained from Middle Georgia was used successfully. The calcined product of the hydrous kaolin can be used as the metakaolin component of the feedstock slurry.

  Novel microspheres exhibiting reduced attrition are generally made from blends of hydrous kaolin particles and calcined kaolin particles. The composition of this blend is typically 25 parts by weight to 75 parts by weight of hydrous kaolin and 75 parts by weight to 25 parts by weight of calcined kaolin. The hydrous kaolin particles, as determined by Sedigraph, have a suitable dispersant added and slurried in water within the solids range of 30-80% by weight limited by the processing viscosity. It has a diameter of 20 to 10 micrometers. Preferably at least 90% by weight of the particles have a size of less than 2 micrometers. Calcined kaolin consists of kaolinite which is formed into spinel (which is also called a defect aluminum-silicon spinel or γ-alumina phase) or mullite by being heated through its exothermic crystalline phase transition. .

The silicate for the binder is preferably provided by sodium silicate in which the ratio of SiO _{2 to} Na ₂ O is 1.5 to 3.5, particularly preferably 2.88 to 3.22.

Next, this binder is added at a level of 0 to 15% by mass (when measured as SiO ₂ ), and then the slurry is spray-dried to obtain ceramic porous beads having an average particle size of 20 to 200 μm. It is formed. The spray dried beads are then heated via an endothermic transition of kaolinite initiated at 550 ° C. to form metakaolin. The resulting microspheres are then crystallized, base-exchanged, calcined, and typically but not always base-exchanged, and a second calcination is performed.

  Before the aqueous slurry is spray dried, an amount of zeolite initiator (e.g., 1 to 30 wt% of kaolin) may be added to the aqueous slurry. As used herein, the term "zeolite initiator" results in a zeolite crystallization process that would not occur in the absence of the initiator or occurs in the absence of the initiator Included are all silica and alumina containing materials that significantly shorten the zeolite crystallization process that would be. Such materials are also known as "zeolite seed crystals". Such zeolitic initiators may or may not exhibit detectable crystallinity by X-ray diffraction.

  The addition of the zeolite initiator to the aqueous slurry of kaolin prior to being spray dried into microspheres is referred to herein as "internal seed addition". Alternatively, it is possible for the zeolite initiator to be mixed with the kaolin microspheres after the formation of the kaolin microspheres before the crystallization process is started, such techniques are referred to herein as " It is called "external seed crystal addition".

  The zeolite initiators used in the present invention can be supplied from a number of sources. For example, the zeolitic initiator can include a recovery of fines generated during the crystallization process itself. Other zeolitic initiators that can be used include fines generated during the crystallization process of other zeolitic products, or amorphous zeolitic initiators in sodium silicate solution. As used herein, "amorphous zeolite initiator" means a zeolite initiator that does not exhibit detectable crystallinity by X-ray diffraction.

  Such seed crystals can be prepared as disclosed in US Pat. No. 4,493,902. Particularly preferred seed crystals are disclosed in US Pat. No. 4,631,262.

  After spray drying, the microspheres may be directly calcined or may be neutralized with an acid to further improve the ion exchange properties of the catalyst after crystallization. The acid neutralization process involves feeding the spray dried, but not calcined, microspheres and mineral acid together into a stirred slurry at a controlled pH. The pH is maintained at about 2-7, most preferably about 2.5-4.5 by adjusting the rate of addition of this solid and acid, but the target pH is about 3. The sodium silicate binder is gelled to form silica and a soluble sodium salt, which is then filtered and washed free of microspheres. Next, the microspheres bound to the silica gel are calcined. In any case, calcination is sufficient to convert all the hydrated kaolin of the microspheres to metakaolin while the pre-calcined kaolin component of the microspheres remains substantially unchanged. Temperature and for a time (e.g., 2 hours in a muffle furnace with a chamber temperature of about 1,350.degree. F.). The resulting fired porous microspheres comprise a mixture of metakaolin and kaolin clay fired via its characteristic exotherm, and these two types of fired kaolin are present in the same microspheres. It is also possible to replace the above-mentioned exothermally calcined kaolin with any suitable calcined alumina.

  As disclosed in U.S. Pat. No. 4,493,902, calcined kaolin microspheres are mixed with an appropriate amount of other components (including at least sodium silicate and water), and then the resulting slurry is The Y-faujasite is crystallized by heating to temperatures and time sufficient to crystallize the Y-fafacite in the microspheres (eg, 10-24 hours at 200-215 ° F.) . It is possible to follow the instructions of US Pat. No. 4,493,902.

  After the crystallization process is complete, the microspheres containing Y-fafacite are separated from at least a substantial portion of the mother liquor, for example by filtration. It may be desirable to wash the microspheres by contacting the microspheres with water either during or after the filtration step. The retained silica is controlled at various levels in the synthesis product. From this silica, silica gel is formed, which imparts functionality towards specific finished product applications.

The filtered microspheres contain Y-form faujasite-type zeolite in sodium form. Typically, the microspheres comprise greater than about 8% Na ₂ O by weight. To produce microspheres as active catalysts, a significant portion of the sodium ions in the microspheres are replaced with ammonium ions or rare earth ions or both.

Ion exchange can be performed by a number of different ion exchange methods. Preferably, the microspheres are first exchanged one or more times with a solution of ammonium salt, eg ammonium nitrate or ammonium sulfate at a pH of about 3. A typical design of base exchange involves a plurality of belt filters which treat the product countercurrent to the exchange solution flow. The number of equilibration stages is determined by optimization of the total sodium and chemical costs to be removed. Typical methods include three to six equilibrium steps in each base exchange method. Ion exchange with ammonium ions is preferably followed by one or more ion exchange with rare earth ions at a pH of about 3. The rare earth may be provided as a single rare earth material or as a mixture of multiple rare earth materials. Preferably, the rare earth is provided in the form of nitrate or chloride. Preferred microspheres of the present invention are ion exchanged to provide 0% to 12% by weight REO, most preferably 1% to 5% by weight REO, and less than about 0.5% by weight, more preferably It contains 0.1% by mass of Na ₂ O. As is well known, it is believed that intermediate firing is required to reach these soda levels.

  After completion of ion exchange, the microspheres are dried. A number of dryer designs can be used including drum, flash and spray drying. The above-described method for ion exchange of the FCC microsphere catalyst of the present invention is well known, and such process itself is not the basis of the present invention.

  The present invention aims at improving the attrition resistance of the zeolite-containing FCC catalyst formed by the above method. For this purpose, cationic polyelectrolytes are added to the kaolin slurry and then processed into a microsphere substrate for subsequent zeolite growth. The addition of this cationic polyelectrolyte results in the addition of this polyelectrolyte if the total catalyst pore volume is the same, as determined by the air jet attrition test (ASTM method D 5757-00) and the roller attrition test. The attrition rate of the resulting FCC catalyst is reduced relative to the control standard catalyst sample produced without. Although the exact mechanism leading to the improvement of attrition is under investigation, polyelectrolytes are known and used in paper coatings and satisfy applications requiring the aggregation of water-containing and calcined kaolin particles. The addition of polyelectrolytes to hydrous and calcined kaolin slurry blends results in a localized structure through the formation of fine aggregates, which are retained during the spray drying and calcination steps of the microsphere formation process Conceivable. The addition of the polyelectrolyte reduces the amount of binder (typically sodium silicate) required without exhibiting an undesirable reduction in the mechanical strength of the microspheres prior to crystallization of the Y-type zeolite. It can also be done.

  The amount of cationic polyelectrolyte added to the kaolin slurry was minimal, and further, a significant improvement in attrition resistance was observed in the finished catalyst. For example, the amount of polyelectrolyte to achieve the desired result was found to be about 0.1 to 10 pounds per ton of dry kaolin (green and calcined). More preferably, 0.5 to 2 pounds per ton, or 0.025 to 0.1% by weight of polyelectrolyte is effectively added, based on the total kaolin content on a dry basis. It is to be understood that the percentage of polyelectrolyte used is based on the total kaolin solids present in the slurry used for microsphere formation prior to zeolite crystallization. The description of the particular method relates to the use of polyelectrolytes with hydrous and calcined kaolin slurries used to form microspheres, but is not limited to such materials. Combinations of suitable polyelectrolytes with other metal oxide precursors which may be used as matrix or future zeolite nutrients may also be used. Nonlimiting examples include alumina, aluminum hydroxide, silica and alumina-silica materials such as clays. The application of the invention described makes use of an in situ FCC manufacturing approach, but can also be easily reworded as being used in an incorporated catalytic process.

Cationic polyelectrolytes useful in the present invention are known in the prior art as fillers for flocculating hydrous kaolin in paper filling and coating applications. Many such agents are also known as flocculants to enhance the filtration rate of clay slurries. See, for example, U.S. Patent Nos. 4,174,279 and 4,767,466. Useful cationic polyelectrolyte flocculants include polyamines, quaternary ammonium salts, diallyl ammonium polymer salts, dimethyldiallyl ammonium chloride (polydadmac). Cationic polyelectrolyte flocculants are characterized by a high positive charge density, which is determined by dividing the total number of positive charges per mole by the molecular weight (M _w ). In general, the M _w of a chemical is estimated to be 10,000 to 1,000,000 (eg, 50,000 to 250,000) at a positive charge density of greater than 1 × 10 ⁻³ . Such materials do not contain anionic groups, such as carboxyl or carbonyl groups. While not wishing to be limited to any particular reaction mechanism, the inorganic cations of clays, such as H ⁺ , Na ⁺ and Ca ^++, are positively associated with cationic polyelectrolytes in the position of the original inorganic cation. It is believed that charged polymer moieties are substituted, and this substitution reduces the negative charge on the clay particles, which in turn results in fusion by mutual attraction. The charge centers near the ends of the polymer chains react and crosslink with adjacent particles until the accessible clay cation exchange centers or polymer charge centers are depleted. This crosslinking strengthens the bonds between the particles, which results in a bulky clay mineral composition with high shear resistance. In the case of dimethyldiallyl ammonium chloride, the presence of chloride ions in the filtrate may be evidence that at least one stage of the reaction between the clay particles and the quaternary salt polymer occurs by an ion exchange mechanism. .

  The Kemira Superfloc C-500 series polyamines are liquid cationic polymers of various molecular weights. It effectively acts as the main flocculant in solid-liquid separation processes in a wide range of industries and charges the neutralizing agent. The range of available chemicals ensures the presence of a product suitable for each individual application. Many if not all of the above products have branched polymer chains.

  BASF MAGNAFLOC LT7989, LT7990 and LT7991 are also polyamines contained in about 50% solution and are useful in the present invention.

In addition to the alkyl diallyl quaternary ammonium salts, other quaternary ammonium cationic flocculants are obtained by copolymerization of aliphatic secondary amines with epichlorohydrin. Other water soluble cationic polyelectrolytes are poly (quaternary ammonium) polyether salts, which contain quaternary nitrogen in the polymer backbone and are chain extended with ether groups. It is prepared from water-soluble poly (quaternary ammonium salts) containing pendant hydroxyl groups and a difunctional reactive chain extender, such polyelectrolytes can be prepared by N, N, N ⁽¹⁾ , N ^{( 1)} -prepared by treating tetraalkylhydroxyalkylenediamines and organic dihalides such as dihydroalkanes or dihaloethers with epoxy haloalkanes. The use of such polyelectrolytes in the aggregation of such polyelectrolytes and clays is disclosed in US Pat. No. 3,663,461.

Example 1
Producing a sample according to the present invention by blending a hydrous and calcined kaolin slurry consisting of 37.5% dry mass of hydrous kaolin and 62.5% dry mass of calcined kaolin to a total slurry solids level of about 50% by mass did. Notable physical properties of the hydrated and calcined kaolin components are listed in Tables 1 and 2. The +325 mesh residue is a coarse material that does not pass through the 325 mesh screen (44 μm spacing between screen meshes). A classification of% less than 1 μm and% less than 2 μm is the mass% of particles having a sphere equivalent diameter measured by Sedigraph 5200 of less than 1 or 2 μm. The calcined kaolin consists of a material heated at about 950 ° C. via a characteristic exothermic transition which often forms a form called spinel phase or mullite phase or a combination of these two phases. The mullite index (MI) is the ratio of mullite peaks in this kaolin sample to a 100% mullite reference sample, this ratio indicates the degree of heat treatment to the calcined kaolin. Apparent bulk density (ABD) is the mass per unit volume of material including porosity. Tap bulk density (TBD) is a measure of bulk density after work done to promote more efficient particle packing, as measured using the TAP-PACK Volumeter (ISO 787-11).

Superfloc C577 (cationic polyamine) per ton of dry clay (both wet and calcined) is mixed into the slurry at a polymer feed of 1.0 dry pounds per ton of dry clay using a standard pneumatic mixer did. The polyamine was diluted to 1% solids prior to feeding the kaolin slurry. Grade # 40 sodium silicate (molar ratio 3.22, or 3.22 parts SiO ₂ per 1.0 part Na ₂ O) was added as a binder at a feed of 4% by weight on a SiO ₂ basis. Apart from that, samples according to the invention were prepared without binder, ie with 0% by weight sodium silicate addition based on SiO ₂ . The slurry was spray dried, thereby forming microspheres having an average particle size (APS) of 80-90 micrometers as measured by laser particle size analysis (Microtrac SRA 150). While the drying method was chosen appropriately, other drying methods are believed to be equally effective in reducing the moisture content of the product to 2% by weight or less (CEM Labwave 9000 moisture analyzer). The resulting microspheres were calcined at 815 ° C. (1500 ° F.) for 1 hour in a laboratory furnace.

Comparative samples were prepared from the same kaolin starting components using the same method, but without the addition of cationic polyamines, and in double the amount of sodium silicate (8% by weight based on SiO _{2 with} respect to kaolin) Was added to this material. In order to change the total pore volume of the resulting microspheres, the amount of added microspheres of the nutrient (nutrient) metakaolin was varied to produce samples I to IE according to the present invention.

Following the formation of the microspheres, zeolite crystallization was performed using the following composition specified in Table 3. Here, the seed crystals are fine aluminosilicate particles, which were used to initiate the crystallization and growth of the zeolite. Sodium silicate (molar ratio, defined as the part of the SiO ₂ to Part Na ₂ O is 1.87) having a composition of SiO ₂ 21.6% by weight and Na ₂ O 11.6 wt%, fine It was recycled and manufactured from the commercial manufacture of balls. Nutrient microspheres consisting mainly of metakaolin soluble in a basic crystallization environment were supplied as a nutrient source for continuous Y-type zeolite growth. The seed crystals used to initiate the zeolite crystallization are described in US Pat. No. 4,493,902 and particularly preferably in US Pat. No. 4,631,262.

  The following method is taken directly from US Patent Application Publication 2012/0228194. As disclosed in U.S. Pat. No. 5,395,809, the disclosure of which is incorporated herein by reference as being part of the present specification, an appropriate amount of calcined kaolin microspheres is used. Mix with other ingredients (including at least sodium silicate and water), and then give the resulting slurry a temperature and time sufficient to crystallize Y-faujasite in the microspheres (eg 200-215) The Y-faujasite was crystallized by heating to 10 ° C for 10 to 24 hours. The microspheres are crystallized to the desired zeolite content (typically about 50-65), filtered, washed, exchanged with ammonium, exchanged with rare earth cations, calcined and ammonium ion with a second time And the second firing was performed.

  Table 4 lists the physical properties of the samples obtained after repeated crystallization followed by ion exchange and calcination. The sample labeled "control" contained no polyamine. The examples according to the invention are designated as polyamines 1A to 1F. Total surface area (TSA), matrix surface area (MSA) and zeolite surface area (ZSA) were measured by BET analysis of nitrogen adsorption isotherms using a Micromeritics TriStar or TriStar 2 instrument. The sample formed in this example provides a high activity / high surface area catalyst, but is not intended to limit the present invention to the surface area or catalytic activity of the formed catalyst. The present invention achieves improved attrition resistance regardless of catalyst activity.

  Initial testing of the prepared catalyst was followed by steaming to simulate the physical properties of the inactivated or equilibrated catalyst from the refinery. The process consists of steaming the catalyst at 1500 ° F. for 4 hours or more. The catalytic porosity was measured by means of mercury porosimetry using a Micromeritics Autopore 4. The total pore volume is the cumulative volume of pores having a diameter in the range of 35-20,000 Å. The unit cell size of the resulting Y-type zeolite microcrystals was measured by the technique described in the ASTM Standard Test Method entitled "Relative Zeolite Diffraction Intensities" (named D 3906-80) or by an equivalent technique.

  FIG. 1 is a plot of air jet attrition results obtained for samples according to the invention and comparative samples versus pore volume. The air jet friability values were measured using an in-house unit according to ASTM Standard Method D5757. For a given catalyst preparation method and composition, the attrition rate increases with increasing porosity of a given catalyst particle. The addition of the polyelectrolyte flocculant prior to the formation of the microspheres alters the packing of the particles that occurs prior to the formation of the microspheres, which results in a more abrasion resistant ceramic structure. In particular, the resulting novel catalyst structures exhibit enhanced durability to attrition caused by wear-type defect mechanisms (abrasion resulting in particles smaller than the original size of the original particles). FIG. 1 demonstrates the observed decrease in attrition rate for the samples according to the invention when the total pore volume is equal to or higher than the comparative example.

FIG. 2 is a plot of the attrition results obtained from the roller attrition tester against the total catalyst pore volume. The roller method is a more severe test which results in an increase in catalytic attrition caused by particle cracking (particles are broken into two or more large parts of the original total particles). Here too, the samples according to the invention showed a decrease in attrition when the total pore volume was equal to or increased (porosity increased to 0.03 cm ³ / g). Samples according to the invention, prepared without the addition of sodium silicate as binder, show improved performance with respect to attrition caused by abrasion, but only in comparison with the control in more aggressive roller tests It was not. Considering that population balance modeling of commercial FCC units indicates that wear is the predominant attrition mechanism over failure, samples formed with polyamines and without binders are compared It is an improvement of the performance step change to the test.

Example 2
The same hydrated and calcined kaolin components were utilized to produce the microspheres of the present invention by varying the amount of Superfloc C577 supply or adding other cationic polyelectrolyte agents. Polyamine addition was carried out as in Example 1 using 4% by weight SiO ₂ as sodium silicate with reduced binder feed. A comparative sample labeled "Control" was formed using 8 wt% SiO ₂ as sodium silicate added prior to spray drying. Tables 5A and 5B show the formulations used to crystallize each microsphere sample to be processed into a finished catalyst.

  An example according to the invention labeled Polyamines: 1A-1F was prepared using Superfloc C577. Polyamines: Samples according to the invention, designated as 1A-1C, were prepared by adding 0.5, 1.0 and 2.0 pounds / ton of polyamine. All samples according to the invention labeled Polyamines: 1C-1F contained 2.0 pounds / ton of charged Superfloc C577, but were formulated to produce a final catalyst of different overall porosity. A sample according to the invention, Polyamine II, was prepared using 1 lb / ton of SuperFloc C572, commercially indicated as a linear low molecular weight polyamine. A sample according to the invention, Polyamine III, was prepared using 1 lb / ton of SuperFloc C 573, which is commercially indicated as branched low molecular weight polyamine. Polyamine IV was prepared using 1 lb / ton of SuperFloc C581, which is commercially indicated as branched high molecular weight polyamine.

  Tables 6A and 6B show physical property data collected from each of the resulting catalyst end products. The attrition results measured by air jet (FIG. 3) and the attrition results measured by roller attrition (FIG. 4) show that the performance of the catalyst of the invention is improved when the total pore volume is comparable to the comparative example Demonstrate that.

Claims (18)

A fluid catalytic cracking (FCC) zeolite containing catalyst which is a zeolite containing microspheres,
The microsphere is
i) formed from a slurry comprising kaolin that has been calcined via exotherm, and ii) zeolite crystals, or iii) either hydrous kaolin and / or metakaolin,
Before or during the formation of the microspheres, the slurry comprises 0.005 to 0.5% by weight of cationic polyelectrolyte based on the weight of i) and ii), or i) and iii) has been mixed with,
The catalyst wherein the slurry is spray dried to form the microspheres, the microspheres are calcined and the zeolite crystals are formed in situ by reacting the microspheres with a silicate .   The catalyst of claim 1, wherein the microspheres are 20 to 200 micrometers.   The catalyst according to claim 1, wherein the microspheres are formed from i) exothermally calcined kaolin, and iii) hydrous kaolin and / or metakaolin, and the zeolite is formed in situ.   The catalyst according to claim 3, wherein the microspheres are formed from i) kaolin that has been calcined via exotherm, and iii) metakaolin.   The catalyst according to claim 3, wherein the microspheres are formed from i) kaolin that has been calcined via exotherm, and iii) hydrous kaolin.   The catalyst according to claim 1, wherein the cationic polyelectrolyte is a polyamine.   5. A catalyst according to claim 4, wherein the cationic polyelectrolyte is a polyamine. Kaolin being fired through the heating of said at least 90 wt% of the particles are formed from ultrafine hydrous kaolin of less than 2 micrometers, the catalyst according to claim 1.   The catalyst according to claim 6, wherein the polyamine is mixed with the slurry in an amount of 0.025 to 0.1 wt% based on the weight of i) and ii), or i) and iii). .   The catalyst according to claim 1, wherein the microspheres are formed from i) exothermally calcined kaolin, and ii) zeolite crystals.   The catalyst according to claim 6, wherein the polyamine has a molecular weight of 10,000 to 1,000,000. A process for the preparation of a fluid catalytic cracking (FCC) zeolite containing catalyst which is a zeolite containing microspheres, comprising the following steps:
forming a slurry comprising i) an exothermally calcined kaolin, and ii) a zeolite crystal, or iii) hydrous kaolin and / or metakaolin.
Mixing the slurry with 0.005 to 0.5 wt% of the cationic polyelectrolyte based on the weight of i) and ii), or i) and iii),
Spray drying the slurry to form microspheres ,
Firing the microspheres , and
Forming zeolite crystals in situ by reacting the microspheres with a silicate .   13. The method of claim 12, wherein the microsphere catalyst has a diameter of 20 to 200 micrometers.   13. The method of claim 12, wherein the cationic polyelectrolyte is a polyamine.   15. The method of claim 14, wherein the polyamine has a molecular weight of 10,000 to 1,000,000.   13. The method according to claim 12, wherein the cationic polyelectrolyte is present in the slurry in an amount of 0.025 to 0.1 wt% based on the weight of i) and ii), or i) and iii). the method of.   The method according to claim 12, wherein the slurry comprises iii) hydrous kaolin and / or metakaolin and the zeolite crystals are formed in situ by reacting the microspheres with a silicate.   13. A method according to claim 12, wherein the exothermally calcined kaolin is formed from ultra-fine hydrated kaolin having at least 90% by weight particles less than 2 micrometers.

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